Temperature regulator



H. S. GANO V TEMPERATURE REGULATOR Filed Oct. 23, 1925 Fig.1.

WITNESSES: INVENTOR Har/an .5. Gama.

Patented Oct. 2, 1928, 1 i

U N E I1 STATES HARLAN S. GANO, OE. PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION 01 PENNSYLVANIA.

rnmrnnarunn uncommon.

I Application filed October 28, 1925. Serial No. 66388.

My invention relates to control systems, and particularly to temperature control systems for heated devices.

' One object of my invention is .to provide a relatively simple and efiicient temperature control system for. a heated-device, U Another object of my invention is to provide a temperature control system that shalb embody means forfpreventing hunting of the system. L A

Another object of my invention is to provide a" temperature control system that shall embody means for varying the energization of the heating means in a series of increments of decreasing lengths of time as thedesired temperature is approached.

In practicing my invention, -I provide an electro-responslve device for selectively energizing an energy-controlling means, a

main thermocouple, subjected to the temperature of the devicebeing heated, for actuating the .electro-responsive device, and a plurality of opposed auxiliary thermocouples connected in series circuit relation with the main thermocouple and selectively energized in accordance with the operation of-the elec-. tro-responsive device; l Inthe single sheet of drawings,

Figure l-is a" diagram of connections .ofa system embodying my invention, and

Fig. 2 is a view, partially in side elevation andpartially in section, of a different form of energy-controlling means.

Referring more particularlyto the control 35 system illustrated in Fig. 1 of the drawings, I have there shown generally a heated device 11 that may, for purposes of illustration, be considered as a furnace that is heated by an electric heating element 12. Both the fur- 4'0 nace structure 11 and the heating means 12 may be of any suitable or desired type, and as they form no part of thepresent invention, are not illustrated or described in detail.

Energi'zation of the heating element 12. is

46 efiected bya transformer- 13 having a-primary winding 141and a. secondary winding 15, the latter being provided with a plurality of taps that are connected to stationary contactterminalmembers, an desired numher ofwhich. maybe provided in accordance with-"the general operation of the entire system. I have illustrated seven contact terminal members designated by ithe'numeral 16. A movable contact arm 17 is provided, that is '6; pivotally' mounted at one of its ends, and' tures onl that may be actuated by a motor armature 18, a suitable mechanical connection therebetween being effected by a shaft 19.- -More or less of the secondary winding will bevin The field winding 21 is connected to a suitable source of-supply of electric energy (not shown) and a motor armature 1,8 is selectively energized, in a manner to be herein-- after described more in detail, in order to effect an operation of the motor armature inf either-a forward or in a reverse direction. Means for controlling the' energization of the heating element 12 comprises an electroresponsive device 22 that is energized by a main thermocouple 23 that is preferably located within the furnace s ructure to be subvice. The thermocouple 23' comprises a pair 'of wires of dissimilar metals as usually employed in the art for'such purposes. While I do not desire to be limited thereto, I may use a couple comprising one wire made of so- ,jected to the temperature ofthe heated de- A called advance metal which is an alloy of copper'and nickel, and another of copper, which is adapted to relativelylow tempera- The outer end of the'advance wire is connected throu ha conductor 24 to one terminal 25 of the e ectro-responsive device-22whieh comprises a moving coil 26, a permanent field magnet 27 and a movable pointer and contact arm 28 -operatively secured to the moving 'coil 26. The other end of the coil 26 is. connected to a terminal member 29 which is connected by aconductor3l to theouter terminal of jthe'copper element of an auxiliary thermocouple 32made of the conductor 34Lto the outer terminal of the same metal element in the thermocouple ele ment. 23. The two auxiliary thermocouples same metals as the'thermocouple 23. The outer end ofthe advance metal element of the l 32 and 33 are located within a suitable casing 35 that is preferably-made of a heat insulatin -m'aterial and that maybe located any- .w relatively to the and I prefer to locate it relatively close to the l ;i ate gm electro-responsive element 22.

It is necessary, when using a thermocouple, to insure a substantially constant temperature for the cold junction in order that the reading or indication of the electro-responsive device energized and controlled by the thermocouple shall be substantially constant. The hereinbefore described connections between the main and the plurality of auxiliary thermocouples, which latter are connected in opposed relation relatively to each other as to the elect'romotive force generated therein, permit of employing 'the three thermocouples while using only a single cold junction, which latter may be located within acasing 36 that is preferably located relatively close to the electro-responsive device 22.

Within the casing 36 there are mounted a heating element 37 and a thermostatic member 38 that are energized from a suitable source of supply of electric energy (not shown), the adjustment of the thermostatic. element 38 being such that the temperature of theends of the conductor 31, which is made of copper, and or the conductor 24 that is made of advance metal, shall be maintained at a substantially constant value, in a manner well known in the art. I a

The indicator arm 28 is adapted to selectively enga e contact members 39 and 41- which may be adjustably mounted within a casing 42 of the electro-responsive device 22, the contact members 39 and 41 being connected to suitable terminal members 011 the outside of the casing 42.

A plurality of contactors 43 and 44 constitute-a part-of the system and severally comprise a pair of upper co-operating contact members 45, a pair of lower co-operating contact members 46 and a pair of operating and holding coils 47. Auxiliary co-operating contact-members 48 are provided'on each of the contactors which open and close simultaneously with the upper contact members 45. The construction of the respective contactors is such that either one or the other of the two 'co-operating contact members 45 and 46 are in engagement in accordance with the energization of the actuating coils 47 The contact member 39 is electrically connected'by a conductor 49 to one terminal of the actuating coil 47 of the contact member 45, the other end thereof being connected through conductors 51 and 52 to one conduc" 'tor of a suitable supply circuit 53 that is here indicated as of negative polarity. The

contact member 41 is connected by a conductor 54 toone terminal of the actuating coil of the contactor 44, the-other end thereof being connected by a conductor 55 to the conductor 525 v ply circuit conductor 56, that is desas of positivepolarity, is connected to a terminal member 57 mounted on the eas- Asu ing 42, which is, in turn, connected to the movable contact arm28. The member 57 is also connected to a conductor 58.that is connected to the stationary contactm'ember of the two co-opera ing members45iof-the two contactors, The fixed contact member of th'e lower sets of co-operating members of the two contactors 43 and 44 are connected together by a conductor 59 and are also connected to-the conductors 52 and 55.

Means for selectively heating and energizing the auxiliary thermocouples 32 and 33 comprise a heating coil 61 that is so located within the casing 35 as to effect heating of the thermocouple 32, when energized, and a heating coil 62 that is so located within the couple 33, when energized. ()ne terminal of each of the heating coils 61 and 62 is con-- nected by a conductor 63 to the conductor 58. The other terminal of the coil 61 is connected through a conductor 64 to one contact member of the auxiliary contacts 48 of the contactor 43, the other contact member being connected through a conductor 65 to -'the conductor 52. The other end of the heating element 62 is connected through a conductor 66 to one contact member of the auxiliary set of contacts of the contactor 44, the other terminal thereof being also connected to the conductor 65 and, therefore, to the conductor 52. I v

The system illustrated more particularly in Fig. 1 of the drawings is shown as applied to an electric heating element, but the system embodying my invention is not limited thereto and may be applied to the control of a gaseous or of a liquid fuel. A furnace structure- 67 is illustrated schematically, and in a frag ment only, in Fig. 2 of the drawings, the fuel entering the furnace structure 67 through a conduit 68 that has an adjustable valve 69 connected therewith. A conduit 71 is connected to the other end of the valve 69 and is suitably connected to a fuel reservoir.

The valve 69 is provided with a screwthreaded stem 72, a gear wheel 73 being mounted thereon and operable'to cause movement of the stem 72 in such manner as to 'vary the amount of fuel that flows through the valve 69. A pinion 74 is mounted on an actuating shaft 75, which shaft may be the same as that mechanically connected to the shaft 19 of the motor armature 18, as shown in Fig. 1 of the drawings. k

The operation of the system embodying my invention is substantially as follows. If it he assumed that the system is connected to a suitable source of. supply and that the heating element 12 is being heated, and that the material being heated in the furnace structure '11, or in the furnace structure 67, is still at a temperature much below a predeterminedtemperature, it is obvious that the electro responsive device 22, and particularly the Ill] movable coil 26, is energized at such a value that the contact-making member 28 is in engagementwith the contact member 39, This ls'obvious from the .fact that the contactmaking-arm 28 ?is to be located intermediate between the members 39 and 41 when the temperatureof the thermocouple 23 is that which it is desired to maintain within the furnace structure, and which is therefore that to which any material located within the furnace structure is to be raised to, or maintained at.

The engagement of the arm 28 with the contact member 39 eifects the closing of an electric circuit from conductor'56' through terminal 57, arm 28, contact member 39, conductor 49, coil 47 of the contactor 43, conductor 52, and from there to the'other supply circuit conductor 53. This effects the actuation of the contactor 43, causing the upper contact members 45 and the auxiliary contact members thereof to engage, and also causing the simultaneous disengagement of the cooperating contact members 46 of that contactor. This effects the closing of an energizing circuit extending from supply circuit conductor 56 through conductor 58, cooperatin contact members 45 of the contactor 43, con uctor 76, armature 18, conductor 77, the

lower set of contact members 46 of the con 7 tactor 44 and conductor 52 to'tlie other side ment 12.

- of the supply circuit 53. The motor armature is actuated in a predetermined direction such that the arm 17 is moved to engage the one or the other of the terminal'members 16 connected to taps on the transformer that will include a greater portion of the secondary winding 15 in the energizing circuit of the heating ele- An auxiliary heating circuit is simultaneously established by and through the auxiliary contacts 48 of the contactor 43 that is traced as follows: from supply circuit conductor 56 through a portion of the conductor 58, conductor 63, through the heating element 61, c0nductor64, co-operating contacts 48 of the contactor 43, conductor 65, conductor 52, and from there to the other supply circuit conductor 53. This latter circuit causes heat to be generated-in the coil 61, thereby energizing the auxiliary thermocouple 32 which generates an auxiliary electromotive force which is additive to that of the main thermocouple 23.

i The effect of this auxiliary thermal elec- -tromotive force is to cause a greater current to" traverse the circuit including the plurality of thermocouples and the moving coil 26,

whereby disengagement between the moving arm-28 and the contact member-39 is effected sooner than would otherwise be the case if the auxiliary thermocouple were not present, vThis means that, if the adjustment within the eleetro-responsive device 22 is such that it Will occupy its neutral or intermediate posi- 'the thermal tion, substantially as shown in Fig. 1 of the drawings, at a predetermined temperature of the thermocouple 23, it will be caused to vbe disengaged from the contact member 39 in advance of the time when the main thermocouple 23 will have reached that predetermined temperature because of the energization of theauxiliary thermocouple.

By such disengagement, the hereinbelore described energizing circuit will be interrupted, and the contactor 43 will be returned to the other of its limiting positions, which is substantially that shown in Fig. 1 of the drawings.

-' As was hereinbefore stated, disengagement of the arm 28 and the contact member 39 is effected in advance of the time that the thermocouple 23 has reached a predetermined temperature, and the material being heated within the structure 11 is, therefore, still belowmal electromotive force in the circuit com-- prising the main and the auxiliary thermocouples and the coil 26, is reduced to such a value that the arm 28 will again be moved to the rleft and re-engage the contact member 39, it will operate to again establishthe here-- inbef ore described energizing circuits to cause the energization of the heating element 12 in the furnace structure 11, and heating coil 61. L

As the temperature of the main thermoof the auxiliary couple 23 is now relatively higher than it was at the beginning of the previous time of energization, the sum of the thermal electromotive forces in the main and the auxiliary thermocouple circuit, will increase idly, and disengagement of the arm 28 and of the contact -member, 39 will be effected in -a shorter time than the previous time of energization. In otherwords, the variation of the energization of the main heating element 12 iselfected in a series of increments of decreasing durations or lengths of time as a predetermined temperature is approached. This method or cycle of operations has the effect of preventing overshooting, or, as it is usually termed, hunting of the system,

which hunting is usually present in case no auxiliar means is provided to prevent the same. uch hunting is ordinarily caused by time lag between the heat generated and its effect upon the controlling de- If, for any reason, the temperaturewithin the furnace structure 11 and, therefore, of

more rapcoils and the auxiliary oppositely-connected.

stantially constant. Hence, I may applfy it the regulat onfof the temperature 0 feed rection opposite to that in which it is caused' to flow when contactor 43 is engaged, and the arm 17 will be caused to engage one or the other of the contact terminal members connected to taps in the primary winding that include a smaller number of turns thereof, thereby reducing the supply of energy of the heating element 12. O

Simultaneously with this connection, the auxiliary heating coil 62 is energized, which efiects energization or the heating of the auxiliary thermocouple 33 that is connected in opposed relation relatively to the thermocouple 32, whereby a thermal electromotive force of the opposite polarity is generated, thereby reducing the thermal electromotive force within this circuitand causing disengggement of the arm 28 of the contact memr 41 in advance of the time that the. thermocouple 23 reachesa predetermined temperature. I

The combination of the auxiliary. heating thermocouples is such that.- it will compensate for the thermal lag inherent in such control devices, and, b -a pro er proportioning thereof, it is possi le to o tain very close regulation of temperature or itsmaintenance at or near a. predetermined value, and to effect a variation of the energizationof a heating means" in a series of increments of decreasing lengths of time as the predetermined temperature is approached.

bly, as hereinbefore-described, is that usual in the art and its operation need not, therefore, be described in detail;

The operation of the system when applied to a aseous or fluid fuel, of the type illustrate generally-in Fig. 2 of the drawings,

is substantially the same and need not, be

further described in detail. 7

While I have illustrated and described the system embodying my invention: as applied to the heating of heated devices,'it. is not limited thereto, as it -may also be applied to various other systems 'or installations in whichheat interchange is to be efiected and in which the temperatureof an -appliance, a deviceor a medium is to be maintained subwater in a power plant, in which case the furnacestructure 11, shown in Fig. ,1 of the drawings, will be replaced by the structure of a feed water heater andthe thermocouple for v of a device} 23 will be thermally associated therewith. The motor comprising the armature 18 and the field winding 21 will be operatively as sociated with means for regulating the amount of fluid or steam entering the feed water heater.

Various modifications and changes may be made without departing from the spirit and scope, of the invention, and I desire, fore, that only such limitations shall be placed thereon as are imposed by the prior art.

I claim as my invention:

1. A temperature controlsystem comprising a contact-making member, an actuating coil therefor, a main thermocouple, subjected to the temperature to be controlled, for energizing said actuating coil, and an auxiliary thermocouple, energized in accordance with the osition of said contact-making member,

preventing hunting of said system.

- 2. In a control system, the combination with a thermocouple subjected to the temperature to be controlled, means for varying the operation of the device to be controlled, an electro-responsive device connected to the thermocouple and adapted to control the means for varying the operation of the device to be controlled, of a second thermocouple connected in electric circuit with the first named thermocouple and enercontrol the means for varying the operation' of the device to The operation of the cold unction assemtrici series circuit relation to the first-named thermocouple and selectively energized in accordance with the operation of said electroresponsive device forpreventing hunting.

4. In a control system, the combination with athermocouple subjected to the temperature of a device to be controlled, means the operation of the device to be contro ed, an electro-responsiv device connected to the thermocouple and adapted to control the means for va the operation of the device to be contro i v le dc of a plurality of opposing auxiliary thermocouples con-.,

therenected in electric series circuit relation to the first-named thermocouple and selectively energized in accordance with the operation of said electro-responsive device for preventing hunting.

5.' In a control system, the combination with a thermocouple subjected to the temper.-

ature of a device to be controlled, means for varying the operation of the device to becontrolled, an electro-responsive device connected to the thermocouple and adapted to control the means for varying the operation of the device to be controlled, of a plurality of thermocouples connected in series circuit relation with the first-named thermocouple, and means for effecting selective energization thereof in accordance with the operation of the electro-responsive device to prevent hunting thereof.

6. In-a control system, the combination with an electro-responsive device for controlling the energization of a heating means, of aplurality of thermocouples connected in series-circuit relation with each other and with the electro-resp'onsive device, and a single cold junction for all of said thermos couples.

7. In a control system, the combination with an electro-respo'nsive device for controlling the energization of a heating means, of a main thermocouple for causing actuation of said electro-responsive device at predetermined temperatures, and auxiliary thermocouples selectively energized in accordance with the operation of said electro-responsive devlce for causing it to be actuated inadvance of the time of reaching said predetermined temperature.

8. In a control system, the combination with an electro-responsive device for controlling the energlzation of a heating means, of a mam thermocouple for causing actuation of said electro-responsive device at predetermined temperatures, a plurality o-f opposed auxiliary thermocouples connected in SGIIGS circuit relation with said main thermocouple,

0nd thermo-couple energized by said heating means for causing said electro-responsive means to be actuated in advance of a temperature at which the first thermo-couple, when acting alone, would be effective to actuate it.

10. The combination with an electro-re-' sponsive device operable to a plurality of positions, and a thermo-couple for actuating said device from one position to another in response to predetermined temperatures of said thermo-couple, of heating means, and a second thermo-couple energized thereby for causing said electro-responsive device to be actuated from one position to another in advance of the temperature at which said first thermo-couple, when acting alone, is efi'ective to actuate it.

In testimony whereof, I have hereunto subscribed my name this 8th day of October, 1925'.

'HARLAN S. GANO. 

